This nonprovisional application claims priority under 35 U.S.C. xc2xa7 119(a) on Patent Application Nos. 69200/2001 filed in Korea on Nov. 7, 2001 and 67254/2002 filed in Korea on Oct. 31, 2002 which are herein incorporated by reference.
1. Field of the Invention
The present invention relates to a method for forming a pattern by a printing process, and particularly, to a method for forming a pattern by a printing process which can easily transfer ink to a transfer roll by adding additive for detachment to easily detach the ink in a groove of a clichxc3xa9 filled with ink at the time of patterning a circuit pattern such as a thin film transistor.
2. Description of the Background Art
Display devices, especially, flat panel display devices such as liquid crystal display devices are provided with an active device such as a thin film transistor in each pixel to drive the display devices. The method for driving the display devices is called an active matrix driving method. In the active matrix method, the active device is arranged at each pixel aligned in matrix form to drive corresponding pixels.
FIG. 1 is a view showing a LCD device using an active matrix method. The LCD device having the illustrated structure is a TFT-LCD using a thin film transistor (TFT) as an active device. As shown, each pixel of the TFT-LCD having Nxc3x97M pixels arranged horizontally and vertically includes a TFT formed at an interconnected region between a gate line 4 to which an injection signal is applied from an external driving circuit and a data line 6 to which an image signal is applied. The TFT includes a gate electrode 3 connected to the gate line 4; a semiconductor layer 8 formed on the gate electrode 3 and activated in accordance with the injection signal being applied to the gate electrode 3; and source/drain electrodes 5 formed on the semiconductor layer 8. At a display region of the pixel 1, formed is a pixel electrode 10 connected to the source/drain electrodes 5 for driving a liquid crystal (not shown) by applying an image signal through the source/drain electrodes 5 in accordance with the semiconductor layer 8 being activated.
FIG. 2 shows a structure of a TFT arranged in each pixel. As shown, the TFT includes a substrate 20 made of a transparent insulating material such as glass; a gate electrode 3 formed on the substrate 20; a gate insulating layer 22 formed on the entire substrate 20 on which the gate electrode 3 is formed; a semiconductor layer 8 formed on the gate insulating layer 22 and activated in accordance with a signal being applied to the gate electrode 3; source/drain electrodes 5 formed on the semiconductor layer 8; and a passivation layer 25 formed on the source/drain electrodes 5 for protecting the device.
The source/drain electrodes 5 of the TFT are electrically connected to a pixel electrode formed in the pixel to drive the liquid crystal and then to display an image in accordance with a signal being applied to the pixel electrode through the source/drain electrodes 5.
In the active matrix type display device such as the liquid crystal display device, a size of each pixel is several tens of xcexcm. Therefore, the active device such as the TFT arranged in the pixel has to be formed having a precision size of several xcexcm. Moreover, as demand for a high picture quality display device such as a high picture quality digital television (HDTV) increases, more pixels have to be arranged on a screen of the same area. Accordingly, the active device patterns (including a gate line pattern and a data line pattern) arranged in the pixel have to be formed with more precision, as well.
To fabricate an active device such as a TFT, a pattern or a line of the active device has to be formed by a photolithography method by an exposure device. However, the photolithography method has a limitation in forming a complex pattern since a photo-resist is formed on a layer to be patterned and then an etching method by a photo process is used. Moreover, since an exposure region of the exposure device is limited at the time of photo-processing of the display device, the photo-processing has to be performed by dividing a screen so as to fabricate a display device of a large area. Accordingly, at the time of processing the divided region, not only matching of a precise location is difficult, but productivity also is lowered since the photo-processing has to be repeated many times.
Therefore, an object of the present invention is to provide a method for forming a pattern, in which a pattern is formed for a display device having a large area by a printing process.
Another object of the present invention is to provide a method for forming a pattern, in which a complex pattern can be formed by coating an additive for detachment in a groove of a clichxc3xa9 filled with ink at the time of printing and then detaching the ink smoothly from the clichxc3xa9.
Still another object of the present invention is to provide a method for forming a pattern, in which transferred ink to a layer to be processed is prevented from being detached through chemical or physical surface processes of the layer to be formed on a substrate.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a method for forming a pattern comprising the steps of: coating an additive for detachment in a groove of a clichxc3xa9 (offset plate) corresponding to a location of a pattern to be formed; filling ink in the groove of the clichxc3xa9 coated by the additive for detachment; and transferring the ink filled in the groove of the clichxc3xa9 to the layer to be processed.
A method for transferring ink to the layer to be processed includes a method using a transfer roll and a method for directly contacting the clichxc3xa9 filled with ink to the layer to be processed.
The clichxc3xa9 is formed of a silicon group material such as SiOX, and additive for detachment corresponding to detachment accelerant is coated in the groove. Therefore, the ink in the groove is smoothly detached from the clichxc3xa9 and easily transferred to the layer to be processed. The layer to be processed is composed of a metal layer, an insulating layer of SiOX or SiNX., and a semiconductor layer has a surface processed either chemically or physically.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.